This invention relates to a machine for SZ-twisting by means of a stationary aperture guide disc and a reversingly driven twisting disc, where the elements to be twisted are fed to the twisting disc (or closer) along a tubular guide and accumulator structure (tubular accumulator) which is arranged concentrically to the twisting axis and extends from the aperture guide disc to the twisting disc.
SZ twisting apparatus, in which the unwinding and pull-off operations are fixed in space, is becoming more and more important in cable manufacturing for a number of reasons. In some cases, a machine for SZ-twisting which is called a tubular accumulator twisting machine and works with a reversibly driven twisting disc, to which the elements to be twisted are fed via a tubular accumulator, has found acceptance.
In twisting with such a tubular accumulator machine, the individual elements are applied in part helically to the outer surface of the tubular accumulator and subsequently pulled off from this surface by means of a pull-off device.
Because the elements in this operation are pulled over the tubular accumulator, a friction coefficient as small as possible is desired therefor in order to keep the tension on the twisting elements low.
In the known tubular accumulator S-Z methods, it is customary to make the tubular accumulator ahead of the alternatingly rotating twisting disc either non-rotatable or freely rotatable, or to rotate it about the longitudinal axis at the speed of the twisting disc. In general, the tubular accumulator is made stationary or it is driven at the speed of the twisting disc, so that no uncontrolled motions of the elements to be twisted relative to the tubular accumulator result under the influence of inertial and friction forces.
In tubular accumulators which are arranged fixed or rotate together with the twisting disc at the same speed of rotation, the problem of the loops of the elements to be twisted on the tubular accumulator backing up either at the beginning or at the end of the tube, i.e., becoming particularly close, arises.
According to experience, the tensile forces to be supplied in passing through the S-Z twisting machine increase more than proportionally with the angle at which the elements to be twisted are looped around the tube. If the distribution of the loops in the longitudinal direction is uneven, particularly large forces must therefore be overcome which can lead to tear-off. It is therefore of interest to distribute the loops uniformly over the tubular accumulator.
The tubular accumulator usually has considerable mass which, if it is rigidly coupled to the twisting disc, makes changing directions more difficult. This change in direction, however, must be executed quickly in order to make the twist changing sections as short as possible.